docs: def getTimeOfClassesRemaining(self,numClasses=0):
          '''
          For checking things like prerequisites, it's useful to check if a requirement is 'almost' met
          '''
          occurrences = EventOccurrence.objects.filter(
              cancelled=False,
              event__in=[x.event for x in self.temporaryeventregistration_set.filter(event__series__isnull=False)],
          ).order_by('-endTime')
          if occurrences.count() > numClasses:
              return occurrences[numClasses].endTime
          else:
              return occurrences.last().startTime